High tension rectifier comprising an auxiliary electrode



Feb. 27, 1934. G, HOLST 1,949,048

HIGH TENSION RECTIFIER COMPRISING AN AUXILIARY ELECTRODE Filed April 14, I928 Patented Feb. 27, 1934 HIGH TENSION RECTIFIER COMPRISING AN AUXILIARY ELECTRODE Gilles Holst, Eindhoven, Netherlands, assignor to N. V. Philips Gloeilampenfabrieken, Eindhoven, Netherlands, a limited liability company of the Netherlands Application April 14, 1928, Serial No. 270,117 In the Netherlands May 6, 1927 6 Claims.

This invention relates to an installation for rectifying alternating current, particularly of high voltage, in which an electric discharge tube is used.

, In discharge tubes adapted for rectifying alternating current of high voltage a discharge of the tube in the wrong direction can be avoided by a sufficiently large distance between the cathode and the anode or anodes. Now, it may occur that in view of this circumstance the distance of the electrodes has to be so large that even in the desired direction the current is established with difficulty. The invention has for its object to obviate this difficulty.

According to the invention an installation for rectifying alternating current comprises a gasfilled electric discharge tube having an incandescent cathode, one or more anodes and one or more auxiliary electrodes for assisting the ignition, said auxiliary electrode or electrodes being connected to the anode of the main discharge tube via another discharge tube having rectifying properties.

This second discharge tube, which hereinafter v will be referred to as auxiliary rectifier, is so connected that in the main discharge tube the path from. the cathode to an auxiliary electrode has the same direction as the path from the cathode to the anode in the auxiliary rectifier so that both the main discharge tube and the auxiliary rectifier allow current to pass in one direction but neither of them give passage to current in the other direction. This results in the auxiliary electrodes of the main discharge tube assuming potentials which can only be positive during the passage of current, for if current passes through the two discharge tubes, the auxiliary electrodes will take a positive potential the value of which depends on the voltage supplied and on the resistance of the path that leads from the cathode of the main discharge tube via the auxiliary electrode and through the auxiliary rectifier to the anode of the main discharge tube. If on the contrary no current passes through the main discharge tube, the auxiliary rectifier is likewise blocked so that the auxiliary electrodes cannot take potentials that may assist a discharge in the wrong direction in the main discharge tube.

Preferably the auxiliary rectifier is connected in series with one or more resistances that limit the current in the circuit of the auxiliary rectifier. Thus a resistance may be connected between each of the auxiliary electrodes and the cathode of the auxiliary rectifier.

In order to intensify the auxiliary discharge a condenser may be connected in parallel with the path of discharge between thecathode and the auxiliary electrode.

In the described installation for rectifying alternating current an electric discharge tube having an incandescent cathode and a gaseous filling may be used in which the distance between the cathode and the anode or anodes is so large that any ignition in the wrong direction is practically prevented, and in which one or more auxiliary electrodes are arranged for assisting the ignition.

The invention will be more clearly understood by reference to the accompanying drawing in which a discharge tube 1 comprises a cathode 2, an anode 3 and two auxiliary electrodes 4 and 5. The cathode is preferably coated with material that readily emits electrons so as to be adapted to sufliciently emit electrons even after but moderate heating. The discharge tube is filled with gas, preferably a rare gas under a pressure of say 3 cm. The distance between the cathode and the anode is so large that even in the absence of the auxiliary electrodes an ignition in the wrong direction cannot take place. The cathode and the anode are connected to the ends of the secondary 9 of a transformer the primary of which is not illustrated. The auxiliary electrodes 4 and 5 and the end of the secondary of the transformer that is connected to the anode have connected between them a rectifier 6 comprising a cathode '7 and an anode 8. As such a high vacuum rectifier may be satisfactorily used. The auxiliary electrodes have connected in series with them resistances 11 and 12 which limit the current in the circuit of the auxiliary rectifier.

At the time that the discharge starts, disregarding the condensers, the potential of the source is applied between the cathode 2 and each of the grids 4 and 5 and plate 3. The gap between the cathode and the plate being the longest, that between the cathode and the grid 4 the next longest, and that between the cathode and grid 5 being the smallest, a discharge will first occur between the cathode and the grid 5; the ionization of the gas-filling in this portion of the discharge path then causes the ignition of the discharge between the cathode and the grid 4, and in a similar manner, the discharge between the cathode and the grid 4 causes the ignition of the discharge between the cathode and the anodes 3. The influence of the condensers 13 and 14 is to intensify the ionization as a result of disruptive discharge. A steadying resistance 10 is mounted in the main circuit. In parallel with the paths of discharge cathode-auxiliary electrodes in the main discharge tube are mounted condensers 13 and 14 which are adapted to intensify the auxiliary discharges. The load, which may be of any desired sort, is schematically indicated at 15, 16.

What I claim is:

1. An installation for the rectification of alternating current, comprising a rectifier tube having a gas-filling, an incandescent cathode, an anode and an auxiliary electrode, the installation comprising an auxiliary discharge tube having rectifying properties, said auxiliary electrode being connected to the anode of said main rectifier tube via said auxiliary discharge tube, and a condenser connected between said auxiliary electrode and said incandescent cathode.

2. A rectifying system comprising a gas-filled space discharge tube having an incandesciole cathode and at least one anode spaced so widely apart that inverse discharge will be inhibited and discharge in the desired direction will occur only with difficulty, the tube also having an auxiliary electrode extending into the discharge space, for facilitating discharge in the desired direction, a source of full wave alternating potential connected across said cathode and anode, means for impressing a positive bias on said auxiliary electrode during the desired half cycle, and a space discharge tube for unbiasing said auxiliary electrode and inhibiting current ilow thereto during the alternate half cycle, and a condenser connected between said auxiliary electrode and said incandescible cathode.

3. A rectifying system comprising a gas-filled space discharge tube having an incandescible cathode and at least one anode spaced so widely apart that inverse discharge will be inhibited and discharge in the desired direction will occur only with difiiculty, the tube also having at least two auxiliary electrodes extending into the discharge space, for facilitating discharge in the desired direction, a source of full wave alternating potential connected across said cathode and anode, and means for impressing a positive bias on said auxiliary electrodes during the desired half cycle.

4. A rectifying system comprising a gas-filled space discharge tube having an incandescible cathode and at least one anode spaced so widely apart that inverse discharge will be inhibited and discharge in the desired direction will occur only with difficulty, the tube also having at least two auxiliary electrodes extending into the discharge space for facilitating discharge in the desired direction, a source of full wave alternating potential connected across said cathode and anode, means for impressing a positive bias on said auxiliary electrodes during the desired half cycle, and a space discharge tube for unbiasing said auxiliary electrodes and inhibiting current flow thereto during the alternate half cycle.

5. A rectifying system comprising a gas-filled space discharge tube having an incandescible cathode and at least one anode spaced so widely apart that inverse discharge will be inhibited and dischar e in the desired direction will occur only with difilculty, the tube also having at least two auxiliary electrodes extending into the discharge space, for facilitating discharge in the desired direction, a source of full wave alternating potential connected across said cathode and anode, means for impressing a positive bias on said auxiliary electrode duri'=.g the desired half cycle, and a space discharge tube for unbiasing said auxiliary electrodes and inhibiting current flow thereto during the alternate half cycle, and a condenser connected between said auxiliary electrodes and said incandescible cathode.

6. A discharge tube comprising a tubular envelope of great length, and a gas-filling, said tube having electrodes including an anode, an incandescible cathode and a plurality of auxiliary electrodes spaced in the discharge path between said anode and cathode, and electric circuits interconnecting said electrodes and means to apply potentials to said electrodes which are increasingly positive from the cathode towards the anode, said auxiliary electrodes upon application of such potentials causing the successive ignition of the portions of said discharge path falling between the cathode and successive auxiliary electrodes to produce a discharge extending from the cathode to the anode.

GILLES HOLST. 

